I've long loved the Found series of magazines and books, where they publish notes and photos found on the street.
Mortified is kind of like that, only the items are not found by strangers, but turned in by the people who wrote them, as signs of how embarrassing they once were (or still are). It includes love notes, diary entries, poems, fiction, photos, etc.
Their site lets you rate and comment on the submissions, which is a lot of fun.
I just bought their two books, Mortified, and Mortified: Love is a Battlefield.
For highlights, check out the Hall of Lame. The classic is "I thought he loved me, till he peed on my car!"